Water-based coolant fluid for engine applications

ABSTRACT

The invention relates to the use of an aqueous solution comprising trimethyl glycine as a coolant fluid in engine applications selected from engines used in automobiles, trucks, motorcycles, aircrafts, trains, tractors, generators, compressors, from stationary engines and equipment, marine engines, power systems, industrial engines, electric engines, fuel cell engines and hybride engines.

FIELD OF INVENTION

The present invention relates to a water-based coolant fluid containingtrimethyl glycine for engine applications, such as engines commonly usedin automobiles, trucks, motorcycles, aircrafts, trains, tractors,generators, compressors, for various stationary engine and equipmentapplications, marine engine applications and the like wherein coolingsystems are used.

BACKGROUND OF INVENTION

The primary role of a coolant fluid is to remove heat and thus cool theengine. The fluid operates in a closed loop system. To provide efficientcooling the fluid must have a high specific heat and thermalconductivity and low viscosity at operating temperatures which generallymay vary in the range of −40° C.-+120° C. Typically internal combustionengines operate at approximately +95° C. The fluid must keep the engineoperational also at subfreezing temperatures and provide maximum freezeprotection.

Normal pressure boiling point elevation is also a beneficial property ofthe fluid in engine coolant applications. Enabling the coolant to removemore heat can be achieved by increasing the system pressure and thus theboiling point of the coolant which allows the coolant to circulate at ahigher maximum temperature.

Another important property of coolants is the corrosion protection theyprovide. Automotive heat exchangers and their construction are wellknown in the art. They contain elastomeric materials, rigid polymericmaterials and multiple metals including aluminium, aluminium alloys,steel, cast iron, brass, solder and copper all of which may with time bedissolved in the working coolant composition within a cooling system byphysical abrasion and chemical action. Automotive manufacturers havetried to reduce car weight to improve fuel efficiency by increasing theuse of aluminium in engines.

During operation of the heat transfer system many factors, particularlyelevated temperatures and contaminants may accelerate corrosion andbecause corrosion is an oxidative process the most critical factor isthe amount of oxygen in the system. In glycol systems oxygen acceleratesthe oxidative degradation of the glycol to form corrosive acids. Forlight-duty automotive applications where the engine operatesintermittently, the corrosion inhibitors must protect the system duringoperation and while idle. Film-forming silicates are widely used forcorrosion protection of heat-emitting aluminium surfaces but they havethe disadvantage of reducing the heat-transfer efficiency of thecoolant, and they react with time with the glycol and any salts to formgels which may cause engine failure.

Cavitation corrosion is a phenomenon which relates particularly tomodern thin-walled automotive engines containing aluminium, particularlyto aluminium cylinder liners and water-pumps which are exposedconstantly to aqueous systems such as internal combustion enginecoolants. Pitting of aluminium surfaces can be detected and further,corrosion products and deposits can interfere with heat transfer.Overheating and engine failure from thermal related stress are possible.

Commercially available engine coolants are generally mixtures of variouschemical components and an alcohol, the preferred alcohols beingselected from the group consisting of ethylene glycol, diethyleneglycol, propylene glycol, dipropylene glycol and mixtures thereof.Usually coolants contain mainly ethylene glycol because of foamingtendency of other alcohols, and other components comprise water andadditional chemical compound which provide corrosion protection. Saidglycols bring about corrosion problems, produce unpleasant odour andthey are rather toxic and they must be treated as hazardous waste.

Engine coolants containing inorganic components like silicates,phosphates, nitrates, borates and nitrites have problems due toinhibition depletion. The depletion of these components, particularlythe silicates have led to concerns about lifetime. High solids loadingfrom inorganic salts presents potential deposit issues. Theprecipitating solids may scale and plug passages within the enginecoolant systems.

Engine coolants based primarily on carboxylic acid technology have beendeveloped. A combination of a monobasic or a dibasic carboxylic acid anda triazole are used in combination with other optional additives.Triazoles are required usually for the protection of yellow metals suchas copper, brass and solder.

Several methods have been proposed for improving properties of enginecoolants. A combination of water soluble phosphate with tungstate,selenate and molybdate for the protection against cavitation corrosionof aluminium is proposed in U.S. Pat. No. 4,548,787.

U.S. Pat. No. 4,404,116 teaches the use of polyhydric alcohols ascorrosion inhibiting and cavitation reducing additives for coolants.

U.S. Pat. No. 4,440,721 discloses the combination of a water-solublephosphate with a water-soluble molybdate, tungstate and selenate forproviding a protective effect against the cavitation corrosion ofaluminium in aqueous liquids.

WO 00/50532 proposes a monocarboxylic acid based antifreeze compositionfor diesel engines. Said formulation comprises a combination of amixture of ethylene or propylene glycol, a monobasic aliphatic organicacid, azoles, low levels of molybdates, a combination of nitrite and/ornitrate salts, polyvinylpyrrolidone, a hydroxide salt, silicates and/orsiloxane stabilized silicates with transition metal compounds whichprovide a protective effect against the cavitation corrosion ofaluminium in aqueous liquids.

WO 97/31988 discloses a non-toxic heat transfer/cooling fluid containingtrimethyl glycine and water for solar panels, refrigeration equipment,ventilation and air-conditioning equipment and heat pumps.

It can be seen that the prevention of cavitation corrosion, particularlyof aluminium in engine applications is a difficult task. Efforts havebeen made in the state of art to solve the problem by the use ofalkylene glycol based formulations and dicarboxylic acid basedformulations with heavy loads of additives. Said formulations resultoften in high solid contents, they are expensive and cause environmentalproblems when discarded. Based on the above it can be seen that thereexists a need for a stable, non-toxic, water-based, non-glycolcontaining coolant fluid for engine applications with superior corrosionprotection and particularly improved inhibition of cavitation corrosionof aluminium.

OBJECT OF THE INVENTION

An object of the invention is to provide a water-based efficient,stable, environmentally acceptable non-toxic coolant fluid for engineapplications with improved cavitation corrosion prevention properties.

A further object of the invention is the use of a water-based trimethylglycine containing fluid as a coolant for engine applications.

The characteristic features of the coolant fluid and its use areprovided in the claims.

SUMMARY OF THE INVENTION

It has been discovered that an aqueous solution containing trimethylglycine, also known as betaine, or salts or derivatives thereof, may beused as a coolant fluid in various engine applications, such as enginescommonly used in automobiles, trucks, motorcycles, aircrafts, trains,tractors, generators, compressors, in stationary engine and equipmentapplications, in marine engine applications, in power systems, inindustrial engines, in electric engines, in fuel cell engines and inhybride engines and the like wherein cooling systems are used, andparticularly in internal combustion engines in automobiles.

DETAILED DESCRIPTION OF THE INVENTION

The coolant fluid according to the invention containing trimethylglycine or salts or derivatives thereof may suitably be used attemperatures ranging between −40-+120° C. According to the invention,said water based coolant fluid comprises trimethyl glycine as ananhydrate or monohydrate, or salts of trimethyl glycine such ashydrochloride, or derivatives of trimethyl glycine such as dimethylglycine, or mixtures thereof. Trimethyl glycine monohydrate is thepreferable compound. Trimethyl glycine, or betaine, may for instance beproduced synthetically or by extracting from natural sources like sugarbeets, thus enabling the production of the water-based coolant fluid ofbiological origin having a favourable life cycle.

According to the invention, the coolant fluid useful in engineapplications comprises 1 to 60% by weight, preferably 20 to 55% byweight of trimethyl glycine as an anhydrate or monohydrate, or salts orderivatives of trimethyl glycine or mixtures thereof, and 40 to 99% byweight, preferably 45 to 80% by weight of water. The water used in saidcoolant fluid compositions is suitably ion exchanged water or tap waterof drinking water quality, preferably ion exchanged water.

The coolant according to the invention performs well even without anyadditives, which can be seen from the examples, but in cases where thereare special requirements for engine coolant fluids, additives known inthe art can be used. However, the amount of additives required issignificantly below the amounts used in the coolants according to thestate of the art.

Additives are selected taking into account the intended object of use ofthe coolant and the compatibility of the chemical compounds. Additives,such as stabilizers, corrosion inhibitors, agents for adjusting theviscosity, surface tension and pH, common in water based enginecoolants, may if desired be added to the coolant fluid. Especially,compounds not harmful to the environment are used. Examples of commonlyused additive/inhibitor mixtures are XLI and AFB from company ChevronTexaco and additive/inhibitor mixture BAYHIBIT from company Bayer. Somesuitable additives are presented in the following.

Antiabrasion agents reduce abrasion of metal components. Examples ofconventional antiabrasion agents are zinc dialkyl thiophosphate and zincdiaryl dithiophosphate. Typical antiabrasion agents also include metalor amine salts of organic sulphur, phosphorus or boron derivatives, orof carboxylic acids. As examples, salts of aliphatic or aromaticC₁-C₂₂-carboxylic acids, salts of sulphurous/sulphuric acids such asaromatic sulphonic acids, phosphorous/prosphoric acids, acid phosphateesters and analogous sulphurous/sulphuric compounds, e.g. thiophosphoricand dithiophosphoric acids, may be mentioned.

Corrosion inhibitors, also known as anticorrosion agents, reduce thedestruction of metal components in contact with the coolant fluid.Examples of corrosion inhibitors include phosphosulphurated hydrocarbonsand products obtained by reacting a phosphosulphurated hydrocarbon withan alkaline earth metal oxide or hydroxide. Further, agents preventingmetals from corroding may also include organic or inorganic compoundssuch as metal nitrites, hydroxylamines, neutralized fatty acidcarboxylates, phosphates, sarcosines and succinimides, etc. Amines suchas alkanol amines, e.g. ethanol amine, diethanol amine and triethanolamine are suitable. Aromatic triazoles may be mentioned as examples ofcorrosion inhibitors of non-iron metal type.

A surface active agent, either non-ionic, cationic, anionic oramphoteric one, may be incorporated into the composition. Examples ofsuitable surface active agents include linear alcohol alkoxylates, nonylphenol ethoxylates, fatty acid soaps, amine oxides, etc.

Antifoam agents may be used to control foaming. Foaming may becontrolled with high molecular weight dimethyl siloxanes and polyethers.Silicone oil and polydimethyl siloxane are some examples of antifoamagents of polysiloxane type.

Detergents and antirust agents for metals include metal salts ofsulphonic acids, alkyl phenols, sulphurized alkyl phenols, alkylsalisylates, naphtenates and other oil soluble mono- and dicarboxylicacids. Very basic metal salts like very basic alkaline earth metalsulphonates (particularly Ca and Mg salts) are often used as detergents.

As examples of suitable viscosity controlling agents, all kinds ofagents known in the field for this purpose like polyisobutylene,copolymers of ethylene and propylene, polymetacrylates, metacrylatecopolymers, copolymers of unsaturated dicarboxylic acid and a vinylcompound, interpolymers of styrene and acrylic esters, and partlyhydrogenated styrene/isopropylene, styrene/butadiene andisoprene/butadiene copolymers as well as partly hydrogenatedhomopolymers of butadiene and isoprene, respectively, may be mentioned.

Antioxidants include alkaline earth metal salts of alkyl phenolthioesters preferably having C₅-C₁₂-alkyl side chains, e.g. calciumnonyl phenol sulphide, barium octyl phenyl sulphide, dioctyl phenylamine, phenyl alphanaphtyl amine, phosphosulphurized or sulphurizedhydrocarbons, etc.

Frictional properties of the coolant fluid may be controlled by means ofagents for adjusting friction. Examples of suitable agents for adjustingfriction include fatty acid esters and amides, molybdenum complexes ofpolyisobutenyl succinic anhydride amino alkanols, glycerol esters ofdimerized fatty acids, alkane phosphonic acid salts, phosphonatecombined with oleamide, S-carboxy alkylene hydrocarbyle succinimide,N-(hydroxyalkyl)-alkenyl succinamic acids or succinimides, di(loweralkyl) phosphites and epoksides, as well as alkylene oxide additionproducts of phosphosulphurated N-(hydroxyalkyl) alkenyl succinimides.

Suspension of insoluble matter present in the coolant fluid during useis assured with dispersing agents, thus preventing the slurry fromflocculating and precipitating or depositing on metal parts.

Mineral oils act as swelling agents for sealing means, and accordingly,they have a swelling effect on the sealing means of the equipment. Theyinclude aliphatic C₈-C₁₃ alcohols such as the tridecyl alcohol.

The coolant fluid may also contain other additional components such asagents for extreme boundary lubrication, additives resisting highpressures, dyes, perfumes, antimicrobial agents and similar agentsfamiliar to those skilled in the art.

The coolant fluid according to the invention has several advantages. Itprevents cavitation corrosion surprisingly well also on aluminiumsurfaces, the foaming of the coolant is insignificant and the coolant ischemically and thermally very stable which results in that there is noneed to replace it frequently. The possible degradation products oftrimethyl glycine, if any, are not corroding compounds. On the contrary,glycol based coolants are usually changed every two to five years and/orinhibitors are added because glycol degrades and the degradationproducts are corrosive compounds. The coolant fluid according to theinvention is non-toxic and as such it may not require hazardous wastetreatment when discarded.

Table I below compares the toxicity of trimethyl glycine with that ofethylene glycol and propylene glycol based on LD₅₀ values found in theliterature. The LD₅₀ values used are tested orally in rats. TABLE ILD₅₀/mg/kg Ethylene glycol 4 700 Propylene glycol 20 000 Trimethylglycine 11 200

Much less additives are needed if any, when compared with conventionalcoolant fluids. Further, additives compatible with trimethyl glycine butincompatible with glycol based coolants, can be used in the coolantfluid according to the invention. Table IIa shows the effect of a fluidcontaining 50% trimethyl glycine on the corrosion of various metalsdetermined as thinning thereof at 40° C. or below: TABLE IIa Copper,Carbon steel Brass, Red metal, Cast iron, Fluid μm/a Fe52, μm/a μm/aμm/a μm/a 50% aqueous solution 1.5 . . . 0.5 75 . . . 10 1.5 . . . 0.2125 . . . 0.2 0.9 . . . 0.2 of trimethyl glycine

Higher values show the corrosion rate at the beginning of the tests,lower values represent the situation stabilized with time.

Table IIb shows the effect of a fluid containing 35% trimethyl glycineon the corrosion of metals. Tap water and MEG 30% (ethylene glycol) andMPG 30% (propylene glycol) were used as reference materials. Corrosiontests were carried out according to the test ASTM 1384 at thetemperature of 50° C. in a closed container of 500 ml. TABLE IIb CastFluid Fe37, iron, Copper, Bronze, Aluminium, (without additives) μm/aμm/a μm/a μm/a μm/a MEG 30% 51 69 0.6 1.4 4.8 MPG 30% 51 40 0.3 1.3 18Water 68 95 1.6 1.7 18 35% aqueous solution 27 61 1.4 1.9 10 oftrimethyl glycine 35% aqueous solution 0.3 22 0.3 0.3 2.4 of trimethylglycine**= with commercial corrosion inhibitor

Table III below shows the effect of trimethyl glycine on freezing pointsof aqueous solutions. TABLE III Fluid Freezing point of a 50% solution,° C. Ethylene glycol −35 Propylene glycol −34 Trimethyl glycine −35

The pH of the coolant fluid keeps always above 7 as trimethyl glycineitself is a buffering substance. Without any pH-adjusting additives thepH of the coolant typically ranges between 8 and 10, with additives itmay range between 8-11.

The lubrication properties of the coolant fluid are significantly betterthan those of corresponding glycol based coolants. Further, the boilingpoint of the coolant fluid under normal pressure is well above 100° C.,for example of a 50% trimethyl glycine solution it is 107-112° C. Thecoolant fluid also has excellent anti-freeze properties.

The coolant fluid gives very good results in glassware corrosion test,hot plate corrosion test and simulated corrosion test. The pH andreserve alkalinity keep in acceptable ranges and the coolant meetsfoaming requirements, particle counting requirements (class 11) andelastomer compatibility requirements. The cavitation corrosion test(Double chamber test) gives very good results with cast iron andaluminium.

The coolant fluid according to the invention can be used in variousengine applications, such as engines commonly used in automobiles,trucks, motorcycles, aircrafts, trains, tractors, generators,compressors, in stationary engine and equipment applications, in marineengine applications, in power systems, in industrial engines, inelectric engines, in fuel cell engines and in hybride engines and thelike wherein cooling systems are used, and particularly in internalcombustion engines in automobiles and in engines and water pumps withsensitive aluminium components. The coolant fluid is also particularlysuitable for protection of equipment/engines under storage andwarehousing.

The invention is illustrated in the following with examples. However,the scope of the invention is not limited to these examples.

EXAMPLES Example 1

Lubrication Properties According to ISO 12156-1

Lubrication properties of aqueous solutions containing 40 wt-% and 50wt-% of trimethyl glycine with commercial conventional inhibitor forengine coolants were compared with commercial engine coolant productscontaining propylene glycol and ethylene glycol using HFFR Lubricationtest ISO 12156-1 at 25° C. The lower numerical value corresponds tobetter lubrication properties. Sample Lubrication/μm Trimethyl glycine40 wt-%, additive 2-6 wt-% 313-361 Trimethyl glycine 50 wt-%, additive2-6 wt-% 285-305 Propylene glycol 39.5 wt-%, containing additives 346Propylene glycol 54.5 wt-%, containing additives 348 Ethylene glycol 37wt-%, containing additives 363 Ethylene glycol 51.5 wt-%, containingadditives 326

Example 2

Corrosion Test for Engine Coolants in Glassware According to ASTM D 1384

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)Mass change (mg/test specimen) Test specimen Before treatment Aftertreatment Copper −0.2 −0.9 Solder −4.3 −5.7 Brass −1.2 −2.0 Steel 0.8Cast iron 1.4 Cast aluminium 13.0 10.1 Coolant characteristics Beforetest After test pH 10.86 8.11 Alkalinity reserve, ml HCl 0.1 M/ASTM D1121 1.81 1.14 Water content (%)/ASTM D 1744 55 56

Example 3

Double Chamber Cavitation Corrosion Test According to CEC C-23-T-99

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)WEIGHT per SPECIMEN, mg After the test and before Before chemical Afterchemical Weight SPECIMEN the test treatment treatment change Cast IronM₁ m₂ m₂ − m₁ (FGL 200) 137703.2 137698.1 −5.1 Aluminium M₁ m₂ m₃ m₃ −m₁ A-5S U3 Y30  50846.0  50854.2 50837.1 −8.9 DATA of the Before AfterENGINE COOLANT TEST TEST pH 10.86 8.50 Reserve Alkalinity 1.8 2.19 WaterContent, % 60.6 58.7

Example 4

Hot Plate Corrosion Test According to ASTM D 4340

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)A. Blanc test Test tube mass (mg) Before preparation m₃ After treatmentm₄ Change (m₄ − m₃) Test tube 1 116524.3 116524.0 0.3 Test tube 2115428.6 115428.4 0.2 Test tube 3 115248.5 115248.3 0.2 Sum of thechanges: S (m4 − m3) 0.7 Changes average m: S (m4 − m3) 0.2 B. Corrosionspeed 30129 Plate temperature (° C.) 135 Liquid temperature (° C.) 130Pressure during the test (pSi) 28 Mass before test (m₁) (mg) 107976.3Mass after test (m₂) (mg) 107970.0 Mass change (m₁ − m₂) (mg) −6.3 Blanctest m (mg) −0.2 Area (cm²) 18.09 Corrosion speed (mg/cm² · week) −0.34Quotation 4 pH before test 10.86 pH after test 8.97 New or used metalspecimen New

Example 5

Simulated Service Corrosion Test According to ASTM D 2570-96

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)

Results: Measure Before test After test PH 10.85 8.00 Alkalinity reserve(mg HCl 0.1 N) 1.81 1.02 Water content (%) 60.5 60.0

TEST 1 Mass change (mg/test specimen) Test specimen Test specimen Beforetreatment After treatment appearance Copper +0.8 −0.1 9 Solder −12.5−13.1 9 Brass −1.7 −1.0 8 Steel −4.2 9 Cast iron −7.0 9 Cast aluminium+17.8 +9.2 88 = Tarnished and slightly discoloured9 = Slight and bright colour

TEST 2 Mass change (mg/test specimen) Test specimen Test specimen Beforetreatment After treatment appearance Copper +0.9 −0.2 9 Solder −13.1−12.7 9 Brass −1.8 −1.3 8 Steel −5.0 9 Cast iron −7.4 9 Cast aluminium+18.0 +8.2 88 = Tarnished and slightly discoloured9 = Slight and bright colour

TEST 3 Mass change (mg/test specimen) Test specimen Test specimen Beforetreatment After treatment appearance Copper +0.5 −0.1 9 Solder −12.0−12.2 9 Brass −1.5 −1.0 8 Steel −4.0 9 Cast iron −6.2 9 Cast aluminium+14.2 +8.0 88 = Tarnished and slightly discoloured9 = Slight and bright colour

AVERAGE Mass change (mg/test specimen) Test specimen Before treatmentAfter treatment Copper +0.7 −0.2 Solder −12.5 −12.7 Brass −1.6 −1.1Steel −4.4 Cast iron −6.9 Cast aluminium +16.7 +8.5

Example 6

Elastomer Compatibility Test According to MF T 46-013

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco),containing no elastomer protecting additives Units Elast. N^(o)1 Elast.N^(o)2 Elast. N^(o)3 Results 6A: Elastomer: RE 3 MVQ INITIAL Length cm75.00 75.00 75.00 75.00 STATE Width cm 13.00 13.00 13.00 13.00 Thicknessmm 0.00 0.00 0.00 0.00 Load g 1.5801 1.6041 1.5455 1.5766 Hardness Pts69 68 68.5 68.5 Stress break Mpa Average (5 tests) 6.3 Strain break %Average (5 tests) 151 AFTER Length cm 75.00 75.00 75.00 75.00 AGEINGWidth cm 13.00 13.00 13.00 13.00 Thickness mm 0.00 0.00 0.00 0.00 Load g1.5974 1.6125 1.5593 1.5897 Hardness Pts 64 64 65 64.3 Stress break Mpa5.0529 5.2927 5.6707 5.3 Strain break % 136.33 146.89 160.89 148VARIATION Length % 0.0 0.0 0.0 0.0 Width % 0.0 0.0 0.0 0.0 Thickness %Load % 1.1 0.5 0.9 0.8 Hardness Pts 1.5 0.7 0.9 1.0 Stress break % −4.5−4.5 −3.5 −4.2 Strain break % −20 −16 −10 −15 −10 −3 7 −2 6B: Elastomer:RE 4 NBR INITIAL Length Cm 75.00 75.00 75.00 75.00 STATE Width cm 13.0013.00 13.00 13.00 Thickness mm 0.00 0.00 0.00 0.00 Load g 1.7109 1.63091.7163 1.6860 Hardness Pts 71 71.5 70.5 71.0 Stress break Mpa Average (5tests) 22.8 Strain break % Average (5 tests) 405 AFTER Length cm 75.0075.00 758.00 302.67 AGEING Width cm 13.00 13.00 13.00 13.00 Thickness mm0.00 0.00 0.00 0.00 Load g 1.7262 1.6466 1.7321 1.7016 Hardness Pts 6970 68 69.0 Stress break Mpa 24.075 24.416 25.115 24.5 Strain break %349.99 359.65 372.17 361 VARIATION Length % 0.0 0.0 910.7 303.6 Width %0.0 0.0 0.0 0.0 Thickness % Load % 0.9 1.0 0.9 0.9 Hardness Pts 0.4 1.21.1 0.9 Stress break % −2.0 −1.0 −3.0 −2.0 Strain break % 6 7 10 8 −14−11 −8 −11 6C: Elastomer: EDPM LS1 INITIAL Length Cm 75.00 75.00 75.0075.00 STATE Width cm 13.00 13.00 13.00 13.00 Thickness mm 0.00 0.00 0.000.00 Load g 1.5225 1.5041 1.5719 1.5328 Hardness Pts 63 63.5 63 63.2Stress break Mpa Average (5 tests) 17.9 Strain break % Average (5 tests)304 AFTER Length cm 75.00 75.00 75.00 75.00 AGEING Width cm 13.00 13.0013.00 13.00 Thickness mm 0.00 0.00 0.00 0.00 Load g 1.5313 1.5132 1.58301.5425 Hardness Pts 59 60 58 59.0 Stress break Mpa 12.132 16.106 15.87714.7 Strain break % 219.03 263.4 281.94 255 VARIATION Length % 0.0 0.00.0 0.0 Width % 0.0 0.0 0.0 0.0 Thickness % Load % 0.6 0.6 0.7 0.6Hardness Pts 1.0 0.6 0.7 0.8 Stress break % −4.2 −3.2 −5.2 −4.2 Strainbreak % −32 −10 −11 −18 −28 −13 −7 −16

Example 7

High Temperature Stability Test of Engine Coolants According to CECC-21-T-00

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)RESULTS: Container wall corrosion dull and slightly Evaluate thecorrosion coloured (8); high type (general or at the colouring at theliquid level) interface liquid/air Deposits content after 1 mldecantation (ml) Liquid coloration Dark Brown after test SUPPLEMENTARYPressure REMARKS 390 kPa

Example 8

Kinematic Viscosity According to ASTM D 445

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)Temperature (° C.) Viscosity (mm²/sec) 100 0.89 40 2.37 20 4.02 0 8.07−20 20.57

Example 9

Oxidation Stability Test According to ASTM D 943

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)

Test conditions:

300 ml oil;

95° C.±0.2° C.;

3 l O₂/h±0.1 l/h;

Iron/copper spiral.

Results: Hours TAN (mg KOH/g) 0 0.01 168 0.14 336 0.25 504 0.46 672 0.67840 0.75 1008 0.73 1176 0.80 1344 1.22 1512 3.65

Example 10

4 Balls Test According to IP 239 (Lubrication)

40 wt-% trimethyl glycine+3 wt-% commercial inhibitor (Chevron Texaco)LOAD WEAR DIAMETER (mm) Average wear Factor Corrected Comp. (kg) 1 2 3 45 6 diameter LD_(h) load (kg) lig. (mm) 6 0.95 8 1.40 10 1.88 0.21 132.67 0.23 16 3.52 0.25 20 4.74 0.27 24 0.14 0.35 0.14 0.38 0.24 0.330.26 6.05 23.3 0.28 32 0.32 0.40 0.30 0.38 0.33 0.35 0.35 8.87 25.3 0.3140 0.40 0.52 0.41 0.49 0.40 0.49 0.45 11.96 26.6 0.33 50 0.46 0.51 0.440.54 0.44 0.49 0.48 16.10 33.5 0.36 63 0.66 0.84 0.68 0.74 0.68 0.840.74 21.86 29.5 0.39 80 1.26 1.30 1.25 1.28 1.24 1.29 1.27 30.08 23.70.42 100 1.68 1.72 1.72 1.72 1.60 1.68 1.69 40.5 24.0 0.46 126 2.04 2.202.08 2.16 2.12 2.28 2.15 55.2 25.7 0.50 160 WELDING 75.8 0.54 200 102.20.59 250 137.5 315 187.1 400 258 500 347 620 462 800 649

1. Use of an aqueous solution comprising trimethyl glycine as a coolantfluid and/or as a protective fluid in engine applications.
 2. Useaccording to claim 1, characterized in that the engine applications areselected from engines used in automobiles, trucks, motorcycles,aircrafts, trains, tractors, generators, compressors, from stationaryengines and equipment, marine engines, power systems, industrialengines, electric engines, fuel cell engines and hybride engines.
 3. Useaccording to claim 1 or 2, characterized in that the engine applicationsare selected from internal combustion engines used in automobiles. 4.Use according to claim 1, characterized in that the engine applicationsare selected from engines and water pumps with aluminium components. 5.Use according to claim 1, characterized in that the coolant fluidcomprises 1 to 60% by weight of trimethyl glycine as an anhydrate ormonohydrate, or salts or derivatives of trimethyl glycine or mixturesthereof.
 6. Use according to claim 1, characterized in that the coolantfluid comprises 20 to 45% by weight of trimethyl glycine as an anhydrateor monohydrate, or salts or derivatives of trimethyl glycine or mixturesthereof.
 7. Use according to any one of claims 1-6 claim 1,characterized in that the coolant comprises additives.